The present invention relates to a paper-stopping mechanism, and more particularly to a paper-stopping mechanism applied in an automatic document feeder for aligning and feeding papers.
An automatic paper-feeding function is essential for an office machine such as fax machine, copy machine, printer or scanner. Those machines include an automatic document feeder (ADF) for feeding papers one by one into the machine.
FIG. 1 is a cross-sectional view illustrating an automatic document feeder (ADF) according to the prior art. As shown in FIG. 1, the automatic document feeder includes a base 11, a pick-up roller 12, a guiding plate 13 and a compressed spring 14. When feeding papers, the compressed spring 14 is adjusted according to the thickness of paper and the paper is fed one by one to the guiding plate 13 and further driven into the base 11 via friction between the paper and the pick-up roller 12 for copying, scanning, faxing or printing. Before entering the guiding plate 13, the paper is stopped and aligned by a paper stopper 15. The paper stopper 15 is controlled by an electromagnetic solenoid (not shown) for switching between a paper-stopping position and a paper-feeding position. As shown in FIG. 2A, the paper stopper 15 is at the paper-stopping position and papers 16 are aligned by the paper stopper 15. When the paper stopper 15 is lifted to the paper-feeding position as shown in FIG. 2B, the papers 16 are fed into the automatic document feeder one by one via a gap 17. However, because the paper stopper is driven by the electromagnetic solenoid according to the prior art, it is costly.
Therefore, the purpose of the present invention is to develop a paper-stopping mechanism applied in an automatic document feeder to deal with the above situations encountered in the prior art.
It is therefore an object of the present invention to propose a paper-stopping mechanism applied in an automatic document feeder for reducing the cost.
It is therefore another object of the present invention to propose a paper-stopping mechanism applied in an automatic document feeder without using any electromagnetic solenoid.
According to the present invention, there is proposed a paper-stopping mechanism applied in an automatic document feeder (ADF). The paper-stopping mechanism includes a shaft, a stepping motor for carrying the shaft to rotate, a cam structure having a first protruding portion and a second protruding portion and carried by the shaft to rotate the first protruding portion and the second protruding portion thereof, a paper-stopping arm having a bearing point, wherein the bearing point is moved against by the first protruding portion to move the paper-stopping arm upward, and an elastic buckling device for buckling the paper-stopping arm when the paper-stopping arm is moving upward to stay at a paper-feeding position, and for shifting when the second protruding portion of the cam structure is rotated against the elastic buckling device for removing the paper-stopping arm from the elastic buckling device to return to a paper-stopping position.
Preferably, the mechanism further includes a one-way clutch disposed between the shaft and the cam structure for providing the cam structure carried by the shaft to rotate in a first direction. Preferably, the shaft carries the one-way clutch to rotate in a second direction when the paper-stopping arm is at the paper-stopping position, the cam structure is caused to rotate in the second direction to be against an end of the elastic buckling device, and the cam structure is stopped to return to an initial position because of a friction between the one-way clutch and the shaft. Preferably, the stepping motor is used to cause the shaft and the cam structure to rotate in the first direction for a fixed angle, and then the paper-stopping arm is moved upward for buckling to stay at the paper-feeding position.
Preferably, the mechanism further includes a base for pivotally connecting the paper-stopping arm to the base, and for fastening the elastic buckling device on the base.
Preferably, the bearing point is a pin. Preferably, the elastic buckling device is a wire spring having a curved point for fastening with the pin of the paper-stopping arm and corresponding with the second protruding portion to rotate against an end of the wire spring to shift for removing the pin of the paper-stopping arm from the curved point and falling down to become the paper-stopping position.
Preferably, the cam structure has an angle between the first protruding portion and the second protruding portion which are alternatively disposed along an axle.
Preferably, the paper-stopping arm includes a first portion and a second portion, and the first portion is pivotally connected to the second portion.
Preferably, the stepping motor is also a stepping motor of the automatic document feeder.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which: